This invention relates to a method for improving a performance of a sputtering target, and more particularly to a method for improving a performance of a sputtering target in a magnetron sputtering system.
During the semiconductor or TFT-LCD (Thin Film Transistor Liquid Crystal Display) manufacturing processes, a sputtering technology generally is used in a thin film deposition. According to the momentum transfer theory, the sputtering technology utilizes the ion of a plasma to be deposited on the deposition element with gas phase, so as to proceed with a thin film deposition.
Presently, the sputter for TFT-LCD is always a magnetron sputtering system. Please refer to FIG. 1 which shows a schematic view of the equipment of the general magnetron sputtering system. In the magnetron sputtering system, a magnet 10 is disposed behind a sputtering target 11 and actuated by a stepper motor. And a substrate 12 is deposited on a plane 13. The magnet 10 is a full-length rectangular form and scans repetitively and retracingly between the two sides of the sputtering target 11. When the magnet 10 approaches the retracing points near the two sides of the sputtering target 11, because of the mechanical efficiency of the stepper motor, the scanning velocity of the magnet 10 can not help but be reduced, even suspended. Thus, the magnetic field at the two sides of the sputtering target will be greater than that at the center thereof, so that the target erosion rate at the two sides of the sputtering target will also be specifically greater than that at the center thereof. This situation causes the restriction of the performance of the expensive sputtering target.
Please refer to FIG. 2 and Table 1. FIG. 2 illustrates an erosion depth measurement of a MoW (tungsten molybdate) alloy target which has been sputtered by a conventional sputter. And Table 1 illustrates a contract table of the same. Among these, the depth of the MoW alloy target 20 is 16 mm. As shown in FIG. 2 and Table 1, the ranges 21, 24, and 27 of the left retracing area 210 and the ranges 23, 26, and 29 of the right retracing area 211 of the MoW alloy target 20 have thicker erosion depth (erosion rate) than the ranges 22, 25, and 28 at the center thereof. Thus, the performance of the MoW alloy target 20 is only 34%.
Please refer to FIG. 3 and Table 2. FIG. 3 illustrates an erosion depth measurement of the Al (aluminum) target which has been sputtered by a conventional sputter. And Table 2 shows a contract table of the same. Among these, the depth of the Al target 30 is 16 mm. As shown in FIG. 3 and Table 2, the ranges 308, 307, 315, 322, 329, 337, 338, 309, 316, 323, 330, and 339 of the downside retracing area 32 and the ranges 302, 301, 310, 317, 324, 331, 332, 303, 311, 318, 325, and 333 of the upside retracing area 31 of the sputtered Al target 30 have thinner residue thickness than the other ranges 304, 312, 319, 326, 334, 305, 313, 320, 327, 335, 306, 314, 321, 328, and 336. Thus, the performance of the Al target 30 is only 33%.
Because of the defects described above, the applicant keeps on carving unflaggingly to develop xe2x80x9cmethod for improving performance of sputtering targetxe2x80x9d through wholehearted experience and research.
It is an object of the present invention to provide a method for improving the performance of a magnetron sputtering system.
It is another object of the present invention to provide a stepwise power controlling method for complying with the scanning position of the magnet in the magnetron sputtering system.
According to an aspect of the present invention, a method for improving a performance of a sputtering target in a magnetron sputtering system having a magnet repetitively, and retracingly scanning between two sides thereof and receiving a power input changing with a scanning position of the magnet includes steps of stepwise reducing the power input while the magnet approaches a specific distance range near a retracing point, so as to reduce an erosion rate of the sputtering target by the magnetron sputtering system, and increasing the power input to a specific value while the magnet leaves the specific distance range, wherein the power input changes with the scanning position of the magnet, so as to improve the performance of the sputtering target.
Preferably, the method is a power changing method.
Preferably, the magnet is controlled by a stepping motor.
Preferably, the power input is supplied by a DC power supply.
Certainly, the power input can be changed by means of revising a computer program of the DC power supply.
Certainly, the power input can be changed by means of revising software of said magnetron sputtering system.
Preferably, the specific distance range has a direct proportion to a scan range of the magnet in magnitude.
Preferably, the sputtering target is made of one selected from a group consisting of an alloy, an oxide, and a metal.
Certainly, the alloy can be one of a tungsten molybdate (MoW) and a neodymium aluminate (AlNd).
Certainly, the oxide can be one of indium tin oxide (ITO) and indium zinc oxide (IZO).
Certainly, the metal can be one of chromium (Cr) and aluminum (Al).
Preferably, the power input is changed stepwise.
In accordance with another aspect of the present invention, a method for improving a performance of a sputtering target in a magnetron sputtering system having a magnet repetitively and retracingly scanning between two sides thereof and receiving a power input changing with a scanning position of the magnet includes steps of defining a scanning center at a substantially half position of a scanning range of the magnet, reducing the power input gradually while the magnet is moved from the scanning center to a retracing point, so as to reduce an erosion rate of the sputtering target by the magnetron sputtering system, and raising the power input gradually while the magnet is moved from the retracing point to the scanning center, wherein the power input changes with the scanning position of the magnet, so as to improve the performance of the sputtering target.
Preferably, the method is a power changing method.
Preferably, the magnet is controlled by a stepping motor.
Preferably, the power input is supplied by a DC power supply.
Certainly, the power input can be changed by means of revising a computer program of the DC power supply.
Certainly, the power input can be changed by means of revising software of said magnetron sputtering system.
Preferably, the scanning range of the magnet has a direct proportion to a distance from the retracing point in magnitude.
Preferably, the sputter target is made of one selected from a group consisting of an alloy, an oxide, and a metal.
Certainly, the alloy can be one of a tungsten molybdate (MoW) and a neodymium aluminate (AlNd).
Certainly, the oxide can be one of indium tin oxide (ITO) and indium zinc oxide (IZO).
Certainly, the metal can be one of chromium (Cr) and aluminum (Al).
Preferably, the power input is changed stepwise.
The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed descriptions and accompanying drawings, in which: